20 amino acids. deceptive---packing is critical
TRANSCRIPT
![Page 1: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/1.jpg)
20 amino acids
![Page 2: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/2.jpg)
![Page 3: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/3.jpg)
![Page 4: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/4.jpg)
![Page 5: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/5.jpg)
Deceptive---packing is critical
![Page 6: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/6.jpg)
Solution crystal structure of the prion monomer
…to Discovery Studio
![Page 7: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/7.jpg)
monomer Dimer (domain swapped)
Expression and crystallization.Human prion protein (90–231)was expressed in E. coli, refolded and purified as described.Crystals, obtained at 20 °C by vapor diffusion with protein at 5 mg/ml and reservoir consisting of 0.1 M Tris-HCl, pH 8, 3 M NaCl and 5 mM CdCl2, were stabilized with 2,4-dimethyl-2,4-pentanediol prior to data collection at –180 °C.
![Page 8: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/8.jpg)
Energy and Stability
A B
If A is favored over B then A is at lower energy…how much lower?
![Page 9: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/9.jpg)
=
RT is thermal energy…the temperature converted into energy units by “R”
![Page 10: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/10.jpg)
=
RT is thermal energy…the temperature converted into energy units by “R”
Our body temperature: 37C or 310 Kelvin or 2600 Joules
![Page 11: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/11.jpg)
=
RT is thermal energy…the temperature converted into energy units by “R”
Our body temperature: 37C or 310 Kelvin or 2600 Joules
If the energy difference is zero, =1 so both are in equal amounts…at equilibriumIf the energy difference is 2600 Joules then B is 2.7 times greater than A
![Page 12: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/12.jpg)
=
RT is thermal energy…the temperature converted into energy units by “R”
Our body temperature: 37C or 310 Kelvin or 2600 Joules/mole
If the energy difference is zero, =1 so both are in equal amounts… at equilibriumIf the energy difference is 2600 J/mole then B is 2.7 times greater than AIf the energy difference is 10 times 2600 J/mole then B is 20,000 times greater than A
![Page 13: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/13.jpg)
=
RT is thermal energy…the temperature converted into energy units by “R”
Our body temperature: 37C or 310 Kelvin or 2600 Joules
If the energy difference is zero, =1 so both are in equal amounts… at equilibriumIf the energy difference is 2600 Joules then B is 2.7 times greater than AIf the energy difference is 10 times 2600 Joules then B is 20,000 times greater than A
If the energy difference is very big then it seems that all of A goes to B
![Page 14: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/14.jpg)
How big is 2600 Joules/mole? …2.6 kJ/moleThe heat needed to melt water molecules: 6 kJ/moleTo break a hydrogen bond: 18-24 kJ/mole
Events happen spontaneously when energy needed is “close” to thermal energy
Energy barrier:
![Page 15: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/15.jpg)
Events happen spontaneously when energy needed is “close” to thermal energy
Energy barrier:
A BC
EnergyA
C
BEnergy change
Energy to get change
Activation energy
For a rate of 1 in 109 sec: energy of 132kJ/moleFor probability of 1 in a million: energy=166kJ/mole
![Page 16: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/16.jpg)
catalyzed catalyzed plus bound changes energy
uncatalyzed
![Page 17: 20 amino acids. Deceptive---packing is critical](https://reader036.vdocuments.us/reader036/viewer/2022081603/56649e895503460f94b8dbce/html5/thumbnails/17.jpg)
Different species…must be stable for multiple animal lifetimesThus very low energy states…deep wells or high energy barriers
…protein must pack very well (low energy) in many different forms or transition structures are highly unstable